Electric protector apparatus.



PATENTED MAR. 28, 1905.

F. B. GO0K..

BLEGTRIO PROTECTOR APPARATUS.

APPLICATION FILED APR.11, 1904.

I nv'enior:

Wi inesses:

No. vseoos.

I UNITED STATES Patented March 28, 1905.

PATENT OFFICE.

ELECTRIC PROTECTOR APPARATUS.

SPECIFICATION forming part of Letters Patent No. 786,005, dated March28, 1905.

l Application filed .pril 11, 1904. Serial No. 202,652.

To all whom it 777/707] concern.-

Be it known that I, FRANK 13. CooK, a citizen of the United States,residing at Chicago, in the county of Cool; and State of Illinois, haveinvented new and useful Improvements in Electric Protector Apparatus, ofwhich the following is a full, clear. concise, and exact description,reference being had to theaccompanying drawings,forming a part of thisspecification.

My invention relates to apparatus for protecting electrical circuits andinstruments against injury from abnormally large currents, my objectbeing, first, to provide an improved and highly efficient form ofprotective apparatus adapted more particularly for use intelephone-circuits; second, to provide an improved and highly-efficientform of heat-coil protector; third, to provide a construction andarrangement whereby the usual testing of the different circuits throughthe apparatus may be accomplished without the necessity of removing theheat-coils from their supports; fourth, to provide an improvedconstruction and arrangement of spring members for closing the circuitof an alarm which is sounded when a heat-coil is operated by anexcessive current; fifth, to provide means for transposing theconductive circuits of certain spring members to connectionterminals onopposite sides of the mounting-plate, and, sixth, to provide certainfeatures of construction which tend to increase the general efiiciencyof a combined thermal protector and lightning-arrester apparatus and tocheapen the manufacture of same.

Electrical transmitting-linesas, for example, telephone or telegraphsystems are liable to suffer from the encroachment of abnormally largecurrents. These trespassing currents may be of distinctly dilferentforms, and consequently a protective device which will effectually guardinstruments or circuits against the encroachment of an intruding currentof one character will be ineffective as far as protecting the circuitsand instruments against a current of another character is concerned. Forexample, there are certain in truding currents which are only slightlyin excess of the normal and which are commonly known as sneak-currents.Again, there are intruding currents of high potential which result fromlightning discharges or severe electrical storms.

In my present invention I have provided an arrangement of apparatuscomprising a thermal protector and a lightning-arrester and suitablemounting and operating springs therefor, adapted to protect electricalcircuits and instruments against both sneak currents and high-potentialcurrents or discharges. The thermal protector which I preferably employcomprises a heat-producing coil and a separable conductor normally heldtogether by a heat-susceptible material, but which is separated by aforce which shears one portion from the other when the heat-susceptiblematerial is softened, and thereby operates a circuit-controlling means.The lightning-arrester employed consists of the usual carbon blocks,with an interposed dielectric. I also provide a socket-switch connectedin circuit with the thermal protector and adapted to receive atesting-plug, the said switch providing means for testing the differentcircuits through the apparatus without necessitating the removal of thethermal protector. I preferably mount the protective apparatus induplicate sets or pairs upon a ground-plate, the duplicate sets of eachpair being on opposite sides of the said plate and adjacent to eachother. The mounting-bolts and respective sleeves therefor are used totranspose certain connection-terminals to opposite sides of theground-plate.

I will more particularly describe my invention by reference to theaccol'npanying drawings, illustrating same, in which Figure l is atransverse section through the protective apparatus, taken on line .2 .2of Fig. 2, showing a pair of protectors mounted upon opposite sides of agroundplatc, one being in an operated position with portions shown inelevation and a test-plug inserted into the ap paratus. Fig.2 is a sideelevation of a number of protectors 'shown in Fig. 1 mounted upon aground-plate. Fig. 3 is a top end view of Fig. 1 without the test-plug.Fig. at shows a modified form of socket-switch for a testplug. Fig. 5 isa cross-section through the thermal protector, taken on line 2 of Fig.2, with portions shown in elevation; and Fig. 6 is a top view of theprotector shown in Fig. 5, with spring m and tonguejshown in dottedlines.

Like characters refer to like parts in the several figures.

The metal plate (Z may be of any suitable character and may be mountedupon a support in any desired position. The protective apparatus for ametallic circuit is arranged in duplicate sets upon opposite sides ofthe plate (Z. Each heat-coil device or thermal protector D is connectedwith a line-spring m, supported upon a bolt 0, which extendstransversely through the said plate (Z. The line-springs m m areconductively connected with the re spective lineterminals 9 and (1 onelinespring on being connected to terminal g through a conducting-sleevet, which is insulated from the bolt 0. The switchboardsprings k, whichare arranged outside of the line-springs m on, one on each side of theplate (Z, are also supported by the said bolt 0 and conductivelyconnected with the respective switchboard-terminalssand 3 oneswitchboard-spring Z: being connected to terminal 8 through the bolt 0.Thus the said springs are arranged in pairs, each pair being composed ofone line-spring and one switchboard-spring and are all insulated fromeach other and from the ground-plate (Z at their mounting by suitableinsulating-sleeves and washers a, mounted upon the said bolt 0. Theauxiliary linesprings 92. a are associated, respectively, with theoppositely-arranged pairs of springs and are, as shown, electricallyconnected with the respective line-springs m m. Consequently both theline-springs m m and the auxiliary line-springs a a are electricallyconnected with the the line-terminals gand 9 By lineterminals it will beunderstood that these are the terminals to which the line conductors ofthe subscribers line are connected, and by switchboard-terminals it willbe understood that these are the terminals to which the conductorsleading to the switchboard are connected. In addition to the auxiliaryline-springs a a there is also an alarmspring Z, associated with eachpair of springs. Normally electrical contact between an alarmspring Zand its line-spring m is prevented by means of a piece of insulation Thefree end of each alarm-spring Z is provided with a bent portion it,adapted to project through an opening in its auxiliary line-spring n andadapted to make contact with the groundstripb when the heat-coiloperates, as shown upon the right of Fig. 1. The free end of eachline-spring m is provided with a bent portion of, Figs. 5 and 6, adaptedto engagea portion got the thermal protector, and with a bent portionj,adapted to make contact with the alarm-springZ when the heat-coiloperates. Each auxiliary linespring a is provided with upturned portions1 ff, adapted to engage the thermal protector l), and thereby hold samein place. A block of insulation w of the protective device I) isinserted between the free ends of each pair of auxiliary line andswitchboard springs 12. and Z:, respectively, the portions f f of spring71 engaging the block o in respective notches f and spring Z; engagingthe block 4: in a notch Z5. Each block 0 is provided with a metalportion 6, adapted to serve as a handle and also to make contact withthe adjacent switchboard-spring Zr and with a hole therethrough adaptedto receive a heat-coil device (Z. Each heat-coil device preferablyconsists of a metallic spool-shaped portion (Z, containing aheat-producing winding (Z the upper end of the spool (Z, Fig. 5, beingbeveled, so as to form a sharp edge adapted to catch in the insulationo, and thus hold the spool in place within the block 4.. The beveled endof spool (Z forms a tight fit in the hole in block 1*, the other end ofspool (Z being provided with a shoulder adapted to limit the insertionof spool (Z into block '0. One terminal of winding (Z is connected tospool (Z, while the other terminal thereof is connected to the handle a.The pin g is c onductively secured to the enlarged end of spool (Z by alayer of solder or other heat-susceptible material :11, as shown in Fig.5. hen the spool (Z is seated in the opening in the block of insulationo and the latter is inserted in place between a pair of springs 7 and a,the pin g is adapted to engage the opening or recess m" in the portion mof the free end of the adjacent linespring at, which is under tensionwhen so engaged, the tension in m tending to shear the heat-susceptiblematerial (1:, and thereby separate the pin 9 from the spool (Z, as shownupon the right of Fig. 1. The winding (Z 3 of each heat-coil ispreferably of suflicient resistance to enable it to generateconsiderable heat upon the passage of a current therein only slightly inexcess of the normal. The switchboard-springs 7t normally bear againstthe metal portions (2 a, respectively, as shown in Fig. 5, thusconnecting the winding (Z and fusible material a; of each heat-coil in aseries circuit with a switchboard-spring Zr and a linespring m.- Thuscurrents traversing the two limbs of a subscribers line must passthrough the line and switchboard springs m m and Z: Z", respectively,and also through the windings (Z (Z and heat-susceptible material row ofthe two heat-coil devices. In other words, there is a pair of springsand a heat-coil device located in each side of the subscribers circuit.Should a current only slightly in excess of the normal show its presencein the circuit, the heat generated by either of the heat-coils will besuflicient to soften the fusible material 1 thereof, and thereby allowthe tension in the adjacent spring m to force the separable conductor 9(Z apart, as shown upon the right of Fig. l, and thereby open the cir-IIC cuit through the protector. l/Vhen the circuit is thus disrupted,thetrespassing current cannot of course find a conducting-path to thedelicate apparatus of the switchboard. W hen a line-spring m isreleased, as by the operation of a heat-coil, the portion thereof makescontact with the adjacent alarm-spring Z, and the portion /L of spring Ithen makes contact with the mounting-strip b. As this strip 0 is ofmetal and as the plate (6 is preferably grounded, it is obvious that aconducting-path is at once established between the line and ground. Thuseach heat-coil in addition to being capable of disrupting thelinecircuit upon the passage of a current slightly in excess of thenormal is also capable when operated of establishing a conducting-pathto ground.

Now with the construction thus described and illustrated it will be seenthat a separable connection. exists between each switchboardspring A andits adjacent heat-coil device. In other words, each switchboard-spring kis capable of being bent away from its adjacent metallic handle 6, so asto open the circuit. With this arrangement the contacts of thetesting-plug P may be readily inserted between the switchboard-springsin 7a and their respec tive contact-pieces e 6. thus enabling thedifferent circuits through the apparatus to be readily tested withoutremoving the heat-coil devices from their supports. In other words, thearrangement comprises a normally closed spring-switch, which isinterposed between each sWitchboard-conductor and the heat-coil allottedthereto and which is in the nature of a spring-jack with normally closedcontacts adapted to be opened by the insertion of the test-plug. Withthis arrangementthe switchboard-circuits and line-circuits through theheat-coils may be tested with but one insertion of the test-plug.Ordinarily heretofore it was necessary to remove the heat-coils fromtheir supports in order to test the line-circuits, and this necessitatedtesting the latter and heat-coilsseparately. VVithmyimprovement,however, it will be seen that it is no longer necessary to remove theheat-coils and that each circuit may be tested without the necessity ofremoving any portion of the protective apparatus.

The test-plug P, which 1 preferably use for testing the circuits throughthe protective apparatus, is shown, described, and claimed in a separateapplication for patent on test-plug for protective apparatus, filed withthis application April 11, 1904, Serial No. 202,653, and comprises pairsof spring-contact members (Z (i e 6 and f f respectively, all mounted onan insulating-block and properly insulated from each other. The springsof each pair are preferably duplicates and are mounted upon oppositeends of the block (0 Springs (i (Z and e e are adapted to be insertedbetween the switchboard-springs 7c 7c and their respectivecontact-pieces e e, as shown in 1, springs (7Z CZ engaging springs Z:7'', respectively, and springs a engaging contactpieces 6 (1,respectively. preferably bent so that their free ends are loosely heldto the block ('6 by pins 0 and are adapted to spring. apart slightly andfit into grooves in the respective carbon lightningarresters 0 0 whenthe plug is inserted. Steps 0 c are prorided to limit the insertion ofthe test-plug into the protective apparatus. The test-plug is preventedfrom lateral displacement by the notches Zi Z)" in the insulation Q?! ofthe respective heat-coil devices, as shown in Fig. 6, which providestrips of insulation at each side of the socket-switches, and by thegrooves in the lightning-arresters c 0, in which the springs f f fit.Springs (Z (Z 6 f andf are connected to conductors l. 2, 8, a, 5, and 6,respectively, which may lead to any suitable testing instrument.

The circuits to be tested are as follows: first, from conductors 1 and 2throughsprings (Z (Z springs l; k, bolt 0, terminals x and s",

and the switchboard-circuit, which is connect' ed to terminals .9 and.9; second, from conductors 3 and 1 through springs e of, contactpiecesa a, heat-c011 windings (Z d, Fig. 5.

spools (Z (Z, fusible material :0 w, pins (1 springs m m,conducting-sleeve t, terminals 4; Q2, and the line-circuit, which isconnected to terminals qand if; third, from conductors 5 and 6 throughsprings f f carbon blocks 0 0, springs 12 a, conducting-sleeve z,terminals (1 Q2, and the line-circuit, which is connected to terminals qand Q2, fourth, from conductor3 through spring a on the left of Fig. 1,contact-piece e, heat-coil winding (Z spool (Z, fusible material :12,pin g, spring on, spring '12 carbon block 0, and spring f to conductor5, and, fifth, from conductor 4 through spring 0 on the right of Fig. 1,contact-piece 0, heatcoil winding (Z spool (Z, fusible material :11, ping, spring m, spring 02., carbon block 0, and spring f to conductor 6.Thus it will be seen that the switchboardcircuit, the linecircuitthrough the heat-coils, the line-circuit direct, or either heat-coil andits contacts may be tested independently of each other without removingthe protective devices from the protective apparatus. Theswitchboard-circuit or line-circuit direct may be tested whether theheat-coils have operated or not.

l/Vith further respect to the construction of the heat-coil devices itwill be seen that the tension of the line-spring m is directed in such amanner that the circuit will be disrupted instantly upon the initialsoftening of the fusible material :10. In other words, the tension ofspring m in each case is utilized to slide the two sections of theseparable conductor one upon the other rather than to pull them directlyapart. In fact, theseparable conductor of each heat-coil device isnormally subjected to a lateral or shearing stress. This,

Springs f f are as stated, results in making the heat-coil del rangementof Fig. 4 a test-plugcanbeinserted vice exceedinglysensitive and readilyresponsive to currents slightly above the normal, due to the fact thattwo surfaces, which are held together by a partially-melted solder orsimilar material, can be more easily and quickly separated by slidingone surface on the other or by subjecting them to a shearing stress thanby attempting to pull them directly apart.

The alarm-conductors Z Zare normally held out of contact with springs mm, respectively, and ground-strip b by insulating-pins 2' i, extendingthrough the springs, and are provided with portions it it, respectively,adapted to make contact with the ground-strip bwhen the heat-coilsoperate, the portions j 7' of springs m m then makingcontact withsprings Z t, as shown upon the right of Fig. 1. With all of thealarm-springs connected in common by conductors p and 9' the operationof any one of the heat-coils will result in-closing the alarm-circuit,which includes the strip 7) and the ground-plate a, upon which all ofthe springs and devices are mounted. It will be seen that the abnormallylarge currents in the line-circuit may as soon as a heat-coil deviceoperates pass from the line through the linespring m and its portion jto the adjacent alarm-spring l, and thence through the por tion 72 ofspring Z to the strip 7) and through the plate a to ground.

As a means for protecting the circuits against high-potential currents,such as result from lightning discharges or severe electrical storms, anumber of lightning-arresters 0 0 are arranged in two parallel rowsalong the metal strip 6. Each lightning-arrester may be of the ordinarytype, consisting of a pair of carbon blocks and an interposeddielectric. The lightning-arresters are held in place against thestrip 1) by the free ends 0/; w of the auxiliary line-springs n 0/,respectively. The high-potential currents ordischarges may pass from theline, through the auxiliary linespring a, the carbon blocks anddielectric of the lightning-arrester 0, the metal strip 7), and theplate (6, to ground, the said currents areing across the gap provided bythe dielectric in a manner well understood. It will be seen that alightning-arrester is associated with each side of the line-circuit, soas to provide protection for each line-conductor entering the exchange.Thus the electrical circuits and instruments are protected againstlightning discharges and high-potential currents, as well as againstsneak-currents.

In Fig. 4. l. have shown a modified form of the socket-switch orspring-jack for making the tests. In this form the socket-switch isarranged near the base of the springs instead of at the top. Theswitchboardterminal s is With this arbetween the spring Z and the shortswitchspring A7 thus placing the testing instrument in circuit fortesting. In either case, however, it will be seen that the protectiveapparatus involves one or more spring-jacks or socket-switches fortesting the different circuits through the apparatus and system and thatin each case it is unnecessary to remove the heat-coil devices orlightning-arresters in making the tests.

As a matter of further and special improvement the free end of eachline-spring m is preferably provided with a slot or cut at", which leadsfrom the notch or recess m" of spring on, as shown in Figs. 5 and 6.\Vith this construction the projecting end portion y of the heat-coildevice can be crowded into the notch on), the bifurcated end of thespring m spreading sufiiciently to allow the said portion g to be heldlirmly in place. In other words, the free end of each line-spring isadapted to grip and iirmly hold the projectii'ig end portion y of theadjacent heat-coil device. lVith this arrangement the pin is firmly heldby the bifurcated spring at after the heat-coil operates, and thereforeno portion of the device is allowed to fall from the apparatus when thesolder is melted by the passage of an abnormally large current in thecircuit.

It will be observed that the construction enables all of the springs toexert whatever tension is necessary in an inwardly direction. None ofthe springs have any movement whatever in an outwardly direction or awayfrom the ground-plate- (t'WllOD the protective devices operate.

While 1 have described and illustrated certain details of constructionin this invention, 1 do not wish to limit same to such particulardetails.

Having thus described my invention, what l claim as new, and desire tosecure by Letters Patent, is

1. A device for protectingelectrical circuits against excessive current,comprising a spring member, a small block ofinsulation removably mountedupon said spring member, said block of insulation being provided with ametallic handle portion and also with an opening or socket, a separableconductor seated in said socket and provided with a heat-concentratingmember, the sections of said separable conductor being held together bysolder, a switchspring engaging the metallic handle portion, and aspring normally under tension and arranged to engage the projecting endportion of said separable conductor, the said solder andheat-concentrating member and second and third mentioned springs allbeing connected in series, and the said metallic contact and secondmentioned spring constituting a normally closed spring-socket switchadapted to receive the connecting-plugof a testing instrument.

IIO

protector seated in a socket in said block of insulation, and aline-spring normally subjecting the projecting end portion of saidthermal protector to lateral pressure, the said metallic contact and itsadjacent spring constituting a normally closed socket-switch forreceiving the contact-plug of a testing instrument.

3. A combined lightning-arrester and thermal-protector apparatuscomprising a metallic support, a number of carbon lightning-arrestersmounted along the edgeof said support, auxiliary line-springs holdingsaid carbon lightning-arrestersin place, a block of insulation removablymounted upon each auxiliary line-spring. a heat-coil device removablymountedin each block of insulation, linesprings normally subjecting theprojecting end portions of said thermal protectors to lateral pressure,contacts on said blocks of insulation, and switchboard-springs engagingsaid contacts, said contacts and switchboard-springs constitutingnormally closed switches, and each switch being adapted to receive theconnecting-plug of a testing instrument.

4. The combination of a thermal protector comprising a block ofinsulation, a spring upon which said block of insulation is mounted, al'ieat-concentrating member and separable conductor mounted on saidblock of insulation, fusible material connecting the sections of saidseparable conductor and adapted to be fused by the heat of saidheat-concentrating member, a spring normally exerting a lateral pressureupon one section of said separable conductor, a fiat contact mounted onsaid block of insulation and connected with said heat-concentratingmember, and another spring normally bearing against said contact, saidlast-mentioned spring and said contact constituting a normally closedswitch-socket adapted to receive a testing-plugz 5. A thermal protectorcomprising a block of insulation, and a pair of springs between whichsaid block of insulation is removably inserted, a heat-concentratingmember and a separable conductor mounted in said block of insulation, acontact mounted on said block of insulation and connected with saidheat-concentrating member, fusible material connecting the sections ofsaid separable conductor and adapted to be fused by the heat of saidheat-concentrating member, said contact being normally engaged by theouter of said springs, and a third spring normally exerting lateralpressure upon one section of said separable conductor, saidlast-mentioned spring, heat-concentrating member, the contact, and saidouter spring, being adapted to be connected in series in a circuit.

6. Apparatus for protecting electrical apparatus against excessivecurrent, comprising a thermal cut-out and a spring-socket switch incircuit therewith, said switch having normally closed contacts and beingadapted to receive the connecting-plug of a testing instrument, asupport upon which the whole is mounted, and the structure includingportions of insulation projecting at each side of said contacts toprevent lateral displacement of the plug.

7. A protective apparatus constructed with a plurality of spring-socketswitches,each having normally closed contacts adapted to be in eluded ina line-circuit, and each adapted to receive the connecting-plugof atesting instrument, protective devices in circuit with the saidswitches, a support upon which the whole is mounted, and portions ofinsulation projecting at each side of said contacts to prevent lateraldisplacement of the plug.

8. Apparatus for protecting electrical circuits against excessivecurrent, comprising thermal cut-outs and spring-socket switches, thesaid switches having normally closed contacts and being adapted toreceive the connecting-plug of a testing instrument, and portions ofinsulation projecting at each side of the said contacts to preventlateral displacement of the plug.

9. A protective apparatus constructed with a plurality of spring-socketswitches adapted to receive the connecting-plugof a testing instrument,each said switch having normally closed contacts adapted to be includedin a circuit, and portions of insulation projecting at each side of thesaid switches and adapted to prevent lateral displacement of the plug.

10. The combination with aground-plate, of a pair of spring members foreach side thereof, mounted thereon and insulated therefrom and from eachother, a block of insulation removably inserted between each pair ofsprings, a thermal protector comprising a heat-producing member, aseparable conductor, and a contact member, mounted on each block of insulation, the said contact member forming a normally closed socket-switchwith the outer spring of the pair, a grooved lightning-arresterremov'ably mounted between the inner spring of each pair and theground-plate, a third spring for each separable conductor and adapted toengage the latter and thereby subject same to a lateral pressure, atest-plug adapted to be inserted into the socket-switches and grooves ofthe lightning-arresters, and held against lateral displacement by thesaid grooves and means at each side of the said switches, and means forgrounding one spring of a pair and closing an alarm-circuit, upon theoperation of a thermal protector, substantially as described.

11. In protective apparatus for electrical circuits, the combination ofa supportingplate; a pair of springs mounted upon said plate butinsulated therefrom and from each other; athermal protector comprisingaheatproducing member, a separable conduct-or and a contact member; saidprotector being removably inserted between said pairs of springs so thatthe said contact member forms a normally closed socket-switch with oneof said springs; a third spring adapted to engage a portion of saidseparable conductor and to laterally separate same under abnormalconditions; and an alarm-spring between the said pair of springs andadapted to control a circuit when the said protector operates.

12. In protective apparatus for electrical circuits, the combination ofa ground-plate; a pair of springs mounted upon said plate but insulatedtherefrom and from each other; a thermal protector comprising aheatconcentrating member, a separable conductor and a metallic handleportion; said protector being removably inserted between the said pairof springs so that the said handle portion forms a normally closedsocket-switch with one of said springs; a lightning-arrester insertedbetween one of said springs and the groundplate, a third spring adaptedto engage a portion of said separable conductor and to laterallyseparate same under abnormal conditions; and an alarm-spring betweensaid pair of springs and adapted to close an alarm-circuit and groundone of said pair of springs, when the thermal protector operates.

13. In apparatus of the class described, a pair of conducting members, apiece of insulating material mounted upon one of said conducting membersand provided with a conductive portion normally engaging the otherconducting member, a thermal protector seated in said piece ofinsulation, and a spring member engaging said protector and beingadapted to control a circuit under abnormal conditions.

14. In apparatus of the class specified, a block of insulation suitablymounted on a support, a thermal protector seated in said insulation, anda conducting member and a spring member in circuit with said protector,the said spring member being allowed to control a circuit upon anabnormal current in the protector.

15. In apparatus of the class specified, a conducting member and a pieceof insulation carried thereby, a spring member, and a thermal protectorseated in said insulation and electrically in circuit with saidconducting member and said spring member, the device being adapted toopen the said circuit upon an abnormal current therein.

16. In apparatus of the class specified, a conducting member and a pieceof insulation carried thereby, a spring member, and an excess-currentoperable device seated in said insulation and electrically in circuitwith said conducting member and said spring member, the latter beingarranged to control a circuit upon the operation of the device.

As inventor of the foregoing l hereunto subscribe my name this 8th dayof April, A. I). 1904:.

FRANK B. COOK.

I/Vitnesses:

JNo. F. TOMPKINS, FREDERICK R. PARKER.

